Hydraulic motors and pumps



May 29, 1962 E. G. KIMSEY HYDRAULIC MOTORS AND PUMPS Filed June 2, 1960 4 Sheets-Sheet 1 Inventor ER/c GEORGE K/MsEY Attorney y 29, 1962 E. G. KlMSEY 3,036,557

HYDRAULIC MOTORS AND PUMPS Filed June 2, 1960 4 Sheets-Sheet 2 Invenlor ER/c GEORGE KIMsEY By m. a MAM.

Attorney y 29, 1962 E. G. KlMSEY Q 3,036,557

HYDRAULIC MOTORS AND PUMPS Filed June 2, 1960 4 Sheets-Sheet 3 ERIC GEORGE Kmsz-rv lnvenlor a Maw. L

Attorney May 29, 1962 E. e. KIMSEY 3,036,557

HYDRAULIC MOTORS AND P UMPS Filed June 2, 1960 4 Sheets-Sheet 4 Inventor ERIC GEORGE K/MSEY Attorney MJM- k it rates t t [ice 3,036,557 HYDRAULIC MGTORS AND PUMPS Eric George Kimsey, 33A Balfour Grove, Friern Barnet, London N20, England Filed June 2, 1960, Ser. No. 33,476 Claims priority, application Great Britain June 4, 1959 11 Elaims. (Cl. 12159) This invention relates to hydraulic motors and may also be applied to hydraulic pumps, but for convenience of description reference is hereinafter made to hydraulic motors.

Hydraulic motors are known comprising a casing having a plurality of hydraulic cylinders grouped about a floating bearing block, and a shaft journalled in said casing having an eccentric working in a cylindrical bore of the bearing block, the hydraulic cylinders being arranged to transmit liquid pressure to the bearing block imparting to it a circular motion with resultant rotation of either the eccentric with the motor shaft or rotation of the motor casing and hydraulic cylinders the shaft remaining stationary.

Such hydraulic motors include mechanical bearing surfaces such as slipper bearings and/ or mechanical connecting rods or equivalent arrangements that complicate the construction.

The general object of the present invention is to provide improvements in hydraulic motors thereby to simplify their construction and increase their eficiency.

A particular object of the invention is to eliminate the previous necessity for mechanical bearing surfaces, connecting rods and such like and their attendant disadvantages.

Another object is to avoid the use of high pressure seals.

Another object is to provide a hydraulic motor capable of running at high pressure, 3,000 or more pounds per square inch, as well as at lower pressures.

Still another object is to avoid the necessity for high precision machining to obtain the required seal on the bearing block surfaces.

With the attainment of these objects in view, the invention provides a hydraulic motor in which the pressure of the liquid admitted to the cylinders in turn one after another during the operation of the motor is made to exert direct thrust on the eccentric without the intermediary of connecting rods. To this end each cylinder has slidable therein a hollow plunger the inner end of which is resiliently constrained into constant sealing contact with a pressure retaining ring carried in the bearing block if the cylinders are carried by the motor casing, and by the motor casing if the cylinders are contained within the bearing block. The pressure retaining ring allows the hydraulic liquid to act over an area within the ring thus keeping the bearing block in balance and also provides for any misalignment between the surface of the bearing block and the inner end of the plunger.

The pressure retaining ring is incorporated to serve a number of further functions such as:

(a) When the liquid is under pressure, the holes through the centre of the ring and the floating bearing block and the plunger allow the liquid pressure, which is creating a load, to act directly on the cylinder head at one end and on the eccentric diameter at the other;

(b) When the liquid is under pressure and due to the rotating action of the eccentric a sliding seal is made between the face of the pressure retaining ring and the base of the hollow plunger where they are in contact;

The pressure retaining ring is positioned in the floating bearing block so that when liquid pressure is applied the thrust is on the centre line of the eccentric;

(d) Sealing between the face of the pressure retaining ring and the base of the hollow plunger is obtained by arranging a suitable differential pressure area between the effective pressure areas of the ring and the plunger; this differential area is made such that an adequate sealing force is achieved between the faces of the ring and the base of the plunger without excessive mechanical bearing pressure on them;

(e) In order to obtain acceptable bearing loads between the sealing faces of the pressure retaining ring and the base of the plunger, grooves or pressure relieving ports are incorporated in the face of the pressure retaining ring which determine the pressure gradient across the sealing face;

(f) If required additional bearing area is obtained on the pressure retaining ring by extending the face of the ring beyond the pressure relieving groove.

Another feature of the invention in one embodiment is that pressure liquid is supplied to the cylinders through the motor shaft and a surrounding sleeve ported in such a way as to ensure balance of the motor shaft and consequently smooth operation with minimum wear. Preferably the discharge of liquid from the cylinders also takes place through the motor shaft and the aforesaid sleeve in which case the porting arrangement may be such that merely by the employment of a simple change-over valve and without any other reversing mechanism, the direction of rotation of the motor shaft or motor casing can be reversed at will.

By way of example some constructional forms of hydraulic motors incorporating the foregoing and other features of the invention are illustrated on the accompanying drawings.

FIGS. 1 and 2 of the drawings show one form, FIG. 1 being partly a cross section and partly an end View, and FIG. 2 being an axial section.

FIGS. 3 and 4 are respectively a plan and a crosssectional elevation of one of the pressure retaining rings.

FIGS. 5 and 6 are views similar to FIGS. 1 and 2 of a form in which the motor shaft is held stationary and the motor casing is arranged to rotate. FIG. 6A shows a constructional detail of this form.

FIGS. 7 and 8 are views similar to FIGS. 1 and 2 but of a mechanically inverted form.

FIG. 9 shows in cross section a modified form of pressure retaining ring.

FIG. 10 similarly shows yet another modified form of pressure retaining ring.

Throughout the several figures of the drawings the same references denote the same or similar parts.

In the hydraulic motor illustrated by FIGS. 1 and 2 there are five hydraulic cylinders 1 grouped about the axis of the motor shaft 7 in a common plane normal to this axis (which plane is hereinafter termed the main cross plane of the motor). These cylinders are held in place in a motor casing or housing 2 having substantially the form of a pentagon in end view, the casing presenting two hubs 3, 4 affording bearings 6, 6 for the motor shaft 7. This shaft has an eccentric 8 in line with the cylinders 1 and arranged to rotate in the cylindrical bore 9 of a bearing block 10 also in the form of a regular pentagon in end view but with its centre coincident with the axis of eccentricity of the eccentric.

A hollow flat-ended plunger 11 is slidable in each hydraulic cylinder 1 and has its inner end face 12 constrained into sealing contact with one of the faces of the pentagon bearing block 10 by a coil spring 13 pressing at its outer end on the head of the cylinder and at its inner end on an internal shoulder 14 of the plunger. A centrally disposed opening 44 in the end face 12 of each plunger 11 communicates with, and is co-axial with, the

hollow interior or chamber 45 of the plunger. A pressure retaining ring 15 for each plunger 11 is incorporated in the bearing block, and the centrally disposed opening 46 in the ring 15 is co-axial with the opening 44 in the end face 12 of the plunger 11 when the latter is retracted to the maximum extent into its cylinder, as is the plunger 11 in the 12 oclock position in FIG. 1. Each pressure retaining ring has an effective area not greater than that of the cylinder bore and is allowed to float to a limited degree of the order of a few thousandths of an inch in a recess in the pentagon bearing block, sealing between the floating bearing block and the pressure retaining ring being achieved by a suitable seal 16. Screws 43 hold the pressure retaining ring in position in the recess but do not interfere with the aforesaid limited floating action.

Five radial ports 17 situated in the aforesaid main cross plane extend from the cylindrical bore 9 of the pentagon bearing block 10, one to each of the five faces of the block and therefore to the interior of the pertaining hydraulic cylinder 1. In the same main cross plane the periphery of the eccentric 8 on the motor shaft 7 is formed with two oppositely situated arcuate grooves 18, 19 separated from one another at both ends by lands 20, 21 constituting in effect valve means that cover and uncover the aforesaid radial ports 17 as the eccentric and the motor shaft rotate.

Two ducts 22, 23 extend along the motor shaft 7 parallel to its axis, these ducts communicating at one end each with one of the aforesaid arcuate grooves 18, 19 in the eccentric 8 and at the other end each with one of two annuli 24, 25 formed adjacent one another in the motor shaft. Asleeve 26 surrounds this end portion of the motor shaft within one of the hubs of the motor casing. This sleeve has a number of radial ports 27, 28 which allow liquid to pass from a circular portion in the hub 4 to the annuli 24, 25. Resilient seals 29' are fitted around the periphery of the sleeve so as to take up any misalignment or wear that may occur. Two radial openings 30, 31 extend through the casing hub 4 one into each reduced portion of the sleeve 26, these openings being screw-threaded for connection to line.

Finally, the interior of the motor casing communicates through a radial port adjacent the eccentric and an axial port in the motor shaft to a drain connection 32 in an end closure for one of the casing hubs.

Assuming the port 31 to be functioning for the time being as the inlet port, the inflowing oilflows along the duct 22 into the arcuate groove 18. The oil then flows through the port 17, the opening 46 in the pressure retaining ring 15, and the opening 44 in the inner end face 12 of the hollow plunger 11 into the plunger chamber 45, the openings 46 and 44 being in continuity with one another and with the plunger interior or chamber 45. The volume of oil now in the hollow plunger 11 acts at one end on the inner face of the cylinder cap and at the other end on the centre line of the eccentric 8 causing the shaft to rotate. The sealing face between the plunger 11 and the pressure retaining ring 15 allows a minute flow of oil into the motor casing or housing 2. As the motor shaft 7 rotates, the land 20 closes and opens the ports 17 allowing oil either to enter or exhaust from the cylinders 1. The exhaust flow is from the chamber 45 of the plunger 11 through the openings 44 and 46 into the arcuate groove 19, along the duct 23 and out through port 30.

With the described construction the porting arrangement is very simple and the provision of the sleeve results in balance of the motor shaft. There are no connecting rods which also leads to simplification. Moreover, by connecting the radial ports 30, 31 through a change-over valve with the supply of pressure liquid and the sump, reversal of rotation of the motor shaft can be efiected at will without any other reversing mechanism being required.

Pressure liquid admitted to each cylinder 1 during the operation of the motor exerts a thrust such that the pressure on the bearing block 16 is counteracted by the pressure on the underside of the block which in turn acts on the eccentric 8 causing it and the motor shaft 7 to rotate. During this rotation each cylinder is cut off from the supply and opened to return line. The plungers 11 in the hydraulic cylinders make sealing contact with the pressure retaining rings housed in the bearing block at all times throughout its motions.

The preferred form of pressure retaining ring is as shown by FIGS. 3 and 4 from which it will be seen that the sealing face has a circumferential groove 40 from which extend escape grooves 41 to the outer edge of the face, thereby to control the pressure gradient across said face.

In the embodiment shown by FIGS. 5, 6 and 6A the motor shaft '7 is held stationary and the motor casing 2 arranged to rotate. The supply of hydraulic liquid is through ports 22A, 23A in the shaft, and the arrangement is such that as the motor casing rotates the bearing block 16 also rotates around the eccentric 8 which remains stationary. The construction apart from the features just mentioned is similar to that of the first described embodiment.

According to FIGS. 7 and 8 the cylinders 1 are contained in the bearing block 10 instead of being carried by the motor casing 2 which, however, has secured to it internal abutments 42 each recessed to receive the pressure retaining ring 15 and the sealing ring 16. It will be apparent that this arrangement is merely the mechanical inversion of that of FIGS. 5, 6 and 6A and that the operation is similar to that already described with reference to these figures.

The modified pressure retaining rings shown in FIG. 9 are deeper than the recesses in the bearing block and each manifests an external flange 15A that engages the pertaining surface of the bearing block 10 outside of the recess in the latter engaged by the portion 15 of the ring and containing the sealing ring 16.

In the alternative modified pressure retaining rings arrangement shown in FIG. 10, each such ring 15 engages a recess formed in the pertaining portion 12 of the plunger 11 and abuts the surface of th bearing block 10. The sealing ring 16 is located in this recess in the end 12 of the plunger 11.

It will be seen that in all the described and illustrated forms of the invention the pressure liquid admitted to the cylinders of the motor exerts direct thrust on the eccentric without the intermediary of connecting rods or the like, and without the necessity for external high pressure seals.

The invention is not limited to the embodiments described 'and illustrated since changes may be made within its scope. For instance, the motor may have a number of hydraulic cylinders other than the five represented.

I claim:

1. A hydraulic motor comprising a casing, a shaft, means journalling said shaft in said casing, an eccentric: on said shaft, a bearing block within said casing and about. said eccentric and having a bore permitting relative rotation between said bearing block and said eccentric, a. plurality of hydraulic cylinders grouped about the axis. of said shaft in a common plane normal to said axis, said cylinders being located in one of the members of the group comprising said casing and said bearing block, a hollow plunger in each cylinder and displaceable therein, means urging said plunger in the direction of the other member of said group, said other member of the group having a recess therein at the interface between said plunger and said other member of said group, a pressureretaining ring located in said recess and adapted to make sealing contact with the plunger urged thereagainst, means holding said ring in position in said recess but permitting said ring to float in said recess to a limited degree of the order of a few thousandths of an inch, said ring and the e,ose,557

plunger end adjacent to said ring having openings in continuity with one another and with the plunger interior, said shaft and eccentric having supply and exhaust passages communicating with said bearing block bore and adapted for connection to hydraulic fluid supply and exhanst means, respectively, means on said eccentric separating said passages from one another at said bore, and said bearing block having a port communicating between its bore and the volume defined by said plunger interior and said openings, whereby fluid admitted to the cylinders in turn one after another during the operation of the motor exerts direct thrust on the eccentric without the intermediary of other mechanical means.

2. A hydraulic motor as set forth in claim 1, including a sealing member adapted to effect sealing between said pressure-retaining ring and the wall of said recess.

3. A hydraulic motor as set forth in claim 2, said pressure-retaining ring having in its face contiguous to said plunger a circumferential groove with which interconnects escape means for the fluid, thereby to control the pressure sealing area and pressure gradient across said face.

4. A hydraulic motor comprising a casing, a shaft, means journalling said shaft in said casing, an eccentric on said shaft, a bearing block within said casing and about said eccentric and having a bore permitting relative rotation between said bearing block and said eccentric, a plurality of hydraulic cylinders grouped about the axis of said shaft in a common plane normal to said axis, said cylinders being in said casing, a hollow plunger in each cylinder and displaceable therein, means urging said plunger in the direction of said bearing block, said bearing block having therein a recess at the interface between said plunger and said bearing block, a pressure-retaining ring located in said recess and adapted to make sealing contact with the plunger urged thereagainst, means holding said ring in position in said recess but permitting said ring to float in said recess to a limited degree of the order of a few thousandths of an inch, said ring and the plunger end adjacent to said ring having openings in continuity with one another and with the plunger interior, said shaft and eccentric having supply and exhaust passage corn municating with said bearing block bore and adapted for connection to hydraulic liquid supply and exhaust means, respectively, means on said eccentric separating said passages from one another at said bore, and said bearing block having a port communicating between its bore and the volume defined by said plunger interior and said openings, whereby liquid admitted to the cylinders in turn one after another during the operation of the motor exerts direct thrust on the eccentric without the intermediary of other mechanical means.

5. A hydraulic motor as set forth in claim 4, in which a sealing member is located about the periphery of said ring at the face thereof contiguous to the bottom of said recess, said sealing member being adapted to effect sealing between said ring and the wall of said recess, and said ring has in its face contiguous to said plunger a circumferential groove with which interconnects escape means for the hydraulic liquid, whereby the pressure sealing area and pressure gradient across said latter face is controlled.

6. A hydraulic motor as set forth in claim 5, said pressure-retaining ring being deeper than said recess, and a peripheral flange on said pressure-retaining ring engaging the surface of said bearing block around said recess.

7. A hydraulic motor comprising a casing, a shaft, means journalling said shaft in said casing, an eccentric on saidshaft, a bearing block within said casing and about said eccentric and having a bore permitting relative rotation between said bearing block and said eccentric, a plurality of hydraulic cylinders grouped about the axis of said shaft in a common plane normal to said axis, said cylinders being located in one of the members of the group comprising said casing and said bearing block, a hollow plunger in each cylinder and displaceable therein,

resilient means urging said plunger in the direction of the other member of said group, said other member of the group having a recess therein at the interface between said plunger and said other member of said group, a pressure-retaining ring located in said recess, means holding said ring in position in said recess but permitting said ring to float in said recess to a limited degree of the order of a few thousandths of an inch, said ring being constrained by said resilient means into constant sealing contact with the plunger end adjacent thereto, said ring and said adjacent plunger end having openings in continuity with one another and with the plunger interior, said shaft and eccentric having supply and exhaust passages communicating with said bearing block bore and adapted for connection to hydraulic fluid supply and exhaust means, respectively, means on said eccentric separating said passages from one another at said bore, and said bearing block having a port communicating between its bore and the volume defined by said plunger interior and said openings, whereby fluid admitted to the cylinders in turn one after another during the operation of the motor fills said volume to form a column which exerts direct thrust on the eccentric without the intermediary of other mechanical means, said ring having in its face contiguous to said adjacent plunger end, groove means controlling the pressure sealing area and pressure gradient across said face.

8. A hydraulic motor comprising a casing, a shaft, means journalling said shaft in said casing, an eccentric on said shaft, a bearing block within said casing and about said eccentric and having a bore permitting relative rotation between said bearing block and said eccentric, a plurality of hydraulic cylinders grouped about the axis of said shaft in a common plane normal to said axis, said cylinders being contained within said bearing block and extending inwards from the peripheral face of said bearing block along axes which are radial to said shaft, a hollow plunger in each cylinder and displaceable therein, abutments on the internal surface of said casing in axial alignment with said cylinders and having recesses in their faces opposed to said cylinders, means urging said plungers in the direction of said abutments, a pressure-retaining ring in each said recess and adapted to make sealing contact with the plunger urged thereagainst, means holding said ring in position in said recess but permitting said ring to float in said recess to a limited degree of the order of a few thousandths of an inch said ring and the plunger end adjacent to said ring having openings in continuity with one another and with the plunger interior, said shaft and eccentric having supply and exhaust pasages communicating with said bearing block bore and adapted for connection to hydraulic fluid supply and exhaust means, respectively, means on said eccentric separating said passages from one another at said bore, and said bearing block having a port communicating between its bore and the volume defined by said plunger interior and said openings, whereby fluid admitted to the cylinders in turn one after another during the operation of the motor exerts direct thrust on the eccentric.

9. A hydraulic motor comprising a casing, a shaft, means journalling said shaft in said casing, an eccentric on said shaft, a bearing block within said casing and about said eccentric and having a bore permitting relative rotation between said bearing block and said eccentric, a plurality of hydraulic cylinders grouped about the axis of said shaft in a common plane normal to said axis, Said cylinders being located in one of the members of the group comprising said casing and said bearing block, a hollow plunger in each cylinder and displaceable therein, means urging said plunger in the direction of the other member of said group, said other member of said group having a recess therein at the interface between said plunger and said other member of said group, a pressure-retaining ring located in said recess and adapted to make sealing contact with the plunger urged thereagainst, means holding said ring in position in said recess but permitting said ring to float in said recess to a limited degree of the order of a few thousndths of an inch, said ring and the plunger end adjacent to said ring having openings in continuity with one another and with the plunger interior, and said bearing block having a port communicating between its bore and the volume defined by said plunger interior and said openings, said eccentric having in its peripheral surface and in said common plane two oppositely situated grooves, lands between adjacent ends of said grooves and adapted sequentially to cover and uncover said ports on relative rotation between said bearing block and said eccentric, said shaft having two annuli adjacent one another and two ducts parallel to the shaft axis, each of said ducts communicating between one of said grooves and one of said annuli, a sleeve mounted about said shaft and covering said annuli, a hub on said casing, said hub having two radial openings adapted for connection, one to a supply of hydraulic liquid and the other to a sump, and communicating each with one of said annuli, the arrangement being such that hydraulic liquid supplied through one of said radial openings is admitted to the cylinders in turn one after another and exerts direct thrust on the eccentric without the intermediary of other mechanical means.

10. A hydraulic motor as set forth in claim 9, including flow-direction changeover means between on the one hand said radial openings and on the other hand said supply of hydraulic liquid and said sump, whereby the motor shaft can be rotated in either direction.

11. A hydraulic motor as set forth in claim 10, includ-i ing resilient sealing members around the periphery of said sleeve, said members being adapted to compensate for misalignment or wear of said sleeve.

References Cited in the file of this patent UNITED STATES PATENTS 598,627 Gifford Feb. 8, 1898 1,562,769 Hubbard Nov. 24, 1925 2,304,903 Eppens Dec. 15, 1942 2,324,291 Dodge July 13, 1943 2,372,523 Sinclair Mar. 27, 1945 FOREIGN PATENTS 1,218,819 France Dec. 21, 1959 

